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Ulmus Laevis
''Ulmus laevis'' Pall., variously known as the European white elm, fluttering elm, spreading elm, stately elm and, in the United States, the Russian elm, is a large deciduous tree native to Europe, from France northeast to southern Finland, east beyond the Urals into Kyrgyzstan and Kazakhstan, and southeast to Bulgaria and the Crimea; there are also disjunct populations in the Caucasus and Spain, the latter now considered a relict population rather than an introduction by man, and possibly the origin of the European population.Fuentes-Utrilla, P., Squirrell, J., Hollingsworth, P. M. & Gil, L. (2006). ''Ulmus laevis (Pallas) in the Iberian Peninsula. An introduced or relict tree species? New data from cpDNA analysis.'' Genetics Society, Ecological Genetics Group conference, University of Wales Aberystwyth 2006. ''U. laevis'' is rare in the UK, although its random distribution, together with the absence of any record of its introduction, has led at least one British authority to cons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter Simon Pallas
Peter Simon Pallas Fellow of the Royal Society, FRS FRSE (22 September 1741 – 8 September 1811) was a Prussian zoologist and botanist who worked in Russia between 1767 and 1810. Life and work Peter Simon Pallas was born in Berlin, the son of Professor of Surgery Simon Pallas. He studied with private tutors and took an interest in natural history, later attending the University of Halle and the University of Göttingen. In 1760, he moved to the University of Leiden and passed his doctor's degree at the age of 19. Pallas travelled throughout the Netherlands and to London, improving his medical and surgical knowledge. He then settled at The Hague, and his new system of animal classification was praised by Georges Cuvier. Pallas wrote ''Miscellanea Zoologica'' (1766), which included descriptions of several vertebrates new to science which he had discovered in the Dutch museum collections. A planned voyage to southern Africa and the East Indies fell through when his father reca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypoxia (environmental)
Hypoxia refers to low oxygen conditions. Normally, 20.9% of the gas in the atmosphere is oxygen. The partial pressure of oxygen in the atmosphere is 20.9% of the total barometric pressure. In water, oxygen levels are much lower, approximately 7 ppm or 0.0007% in good quality water, and fluctuate locally depending on the presence of photosynthetic organisms and relative distance to the surface (if there is more oxygen in the air, it will diffuse across the partial pressure gradient). Atmospheric hypoxia Atmospheric hypoxia occurs naturally at high altitudes. Total atmospheric pressure decreases as altitude increases, causing a lower partial pressure of oxygen, which is defined as hypobaric hypoxia. Oxygen remains at 20.9% of the total gas mixture, differing from hypoxic hypoxia, where the percentage of oxygen in the air (or blood) is decreased. This is common in the sealed burrows of some subterranean animals, such as blesmols. Atmospheric hypoxia is also the basis of altitude tra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosperm plants. Seeds are the product of the ripened ovule, after the embryo sac is fertilized by sperm from pollen, forming a zygote. The embryo within a seed develops from the zygote, and grows within the mother plant to a certain size before growth is halted. The seed coat arises from the integuments of the ovule. Seeds have been an important development in the reproduction and success of vegetable gymnosperm and angiosperm plants, relative to more primitive plants such as ferns, mosses and liverworts, which do not have seeds and use water-dependent means to propagate themselves. Seed plants now dominate biological niches on land, from forests to grasslands both in hot and cold climates. The term "seed" also has a general me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ciliate
The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagellum, eukaryotic flagella, but are in general shorter and present in much larger numbers, with a different wikt:undulating, undulating pattern than flagella. Cilia occur in all members of the group (although the peculiar Suctoria only have them for part of their biological life cycle, life cycle) and are variously used in swimming, crawling, attachment, feeding, and sensation. Ciliates are an important group of protists, common almost anywhere there is water—in lakes, ponds, oceans, rivers, and soils. About 4,500 unique free-living species have been described, and the potential number of extant species is estimated at 27,000–40,000. Included in this number are many Ectosymbiosis, ectosymbiotic and endosymbiotic species, as well as some Obligate parasite, obligate and Facultative parasite, opportunistic parasites. Ciliate species r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Samara (fruit)
A samara (, ) is a winged achene, a type of fruit in which a flattened wing of fibrous, papery tissue develops from the ovary wall. A samara is a simple dry fruit, and is indehiscent (not opening along a seam). The shape of a samara enables the wind to carry the seed farther away from the tree than regular seeds would go, and is thus a form of anemochory. In some cases the seed is in the centre of the wing, as in the elms (genus ''Ulmus''), the hoptree (''Ptelea trifoliata''), and the bushwillows (genus ''Combretum''). In other cases the seed is on one side, with the wing extending to the other side, making the seed autorotate as it falls, as in the maples (genus '' Acer'') and ash trees (genus ''Fraxinus''). There are also single-wing samara such as mahogany (genus Swietenia) which have a shape that enables fluttering. Some species that normally produce paired samaras, such as ''Acer pseudoplatanus'', can also produce them in groups of three or four. File:TripleSycamoreS ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particular have long propagated using the movements of humans and animals in a symbiotic relationship that is the means for seed dispersal for the one group and nutrition for the other; in fact, humans and many animals have become dependent on fruits as a source of food. Consequently, fruits account for a substantial fraction of the world's agricultural output, and some (such as the apple and the pomegranate) have acquired extensive cultural and symbolic meanings. In common language usage, "fruit" normally means the seed-associated fleshy structures (or produce) of plants that typically are sweet or sour and edible in the raw state, such as apples, bananas, grapes, lemons, oranges, and strawberries. In botanical usage, the term "fruit" also i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanism for the union of sperm with eggs. Flowers may facilitate outcrossing (fusion of sperm and eggs from different individuals in a population) resulting from cross-pollination or allow selfing (fusion of sperm and egg from the same flower) when self-pollination occurs. There are two types of pollination: self-pollination and cross-pollination. Self-pollination occurs when the pollen from the anther is deposited on the stigma of the same flower, or another flower on the same plant. Cross-pollination is when pollen is transferred from the anther of one flower to the stigma of another flower on a different individual of the same species. Self-pollination happens in flowers where the stamen and carpel mature at the same time, and are positi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apetalous
Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corolla''. Petals are usually accompanied by another set of modified leaves called sepals, that collectively form the ''calyx'' and lie just beneath the corolla. The calyx and the corolla together make up the perianth, the non-reproductive portion of a flower. When the petals and sepals of a flower are difficult to distinguish, they are collectively called tepals. Examples of plants in which the term ''tepal'' is appropriate include genera such as ''Aloe'' and ''Tulipa''. Conversely, genera such as ''Rosa'' and '' Phaseolus'' have well-distinguished sepals and petals. When the undifferentiated tepals resemble petals, they are referred to as "petaloid", as in petaloid monocots, orders of monocots with brightly colored tepals. Since they include Liliales, an alternative n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leaf Shape
The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular or irregular, may be smooth or bearing hair, bristles or spines. For more terms describing other aspects of leaves besides their overall morphology see the leaf article. The terms listed here all are supported by technical and professional usage, but they cannot be represented as mandatory or undebatable; readers must use their judgement. Authors often use terms arbitrarily, or coin them to taste, possibly in ignorance of established terms, and it is not always clear whether because of ignorance, or personal preference, or because usages change with time or context, or because of variation between specimens, even specimens from the same plant. For example, whether to call leaves on the same tree "acuminate", "lanceolate", or "linear" could ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leaf
A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, flower, and fruit collectively form the shoot system. In most leaves, the primary photosynthetic tissue is the palisade mesophyll and is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of ''Eucalyptus'', palisade mesophyll is present on both sides and the leaves are said to be isobilateral. Most leaves are flattened and have distinct upper (adaxial) and lower ( abaxial) surfaces that differ in color, hairiness, the number of stomata (pores that intake and output gases), the amount and structure of epicuticular wax and other features. Leaves are mostly green in color due to the presence of a compound called chlorophyll that is essential for photosynthesis as it absorbs light ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diameter At Breast Height
Diameter at breast height, or DBH, is a standard method of expressing the diameter of the trunk or bole of a standing tree. DBH is one of the most common dendrometric measurements. Tree trunks are measured at the height of an adult's breast, which is defined differently in different countries and situations. In many countries, DBH is measured at approximately above ground. Global variation and scientific precision The height can make a substantial difference to the measured diameter. In the United States, DBH is typically measured at above ground. In some countries, such as Australia, New Zealand, Burma, India, Malaysia, and South Africa, breast height diameter has historically been measured at a height of , but because of much active research into allometrics that are being applied to trees and forests, the convention of is more appropriate. Ornamental trees are usually measured at 1.5 metres above ground. Some authors have argued that the term DBH should be aboli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wych Elm
''Ulmus glabra'' Hudson, the wych elm or Scots elm, has the widest range of the European elm species, from Ireland eastwards to the Urals, and from the Arctic Circle south to the mountains of the Peloponnese and Sicily, where the species reaches its southern limit in Europe; it is also found in Iran. A large deciduous tree, it is essentially a montane species, growing at elevations up to , preferring sites with moist soils and high humidity.Heybroek, H. M., Goudzwaard, L, Kaljee, H. (2009). ''Iep of olm, karakterboom van de Lage Landen'' (:Elm, a tree with character of the Low Countries). KNNV, Uitgeverij. The tree can form pure forests in Scandinavia and occurs as far north as latitude 67°N at Beiarn in Norway. It has been successfully introduced as far north as Tromsø, Norway and Alta, Norway (70°N). It has also been successfully introduced to Narsarsuaq, near the southern tip of Greenland ( 61°N). The tree was by far the most common elm in the north and west of the Britis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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